1. Field of the Invention
Apparatus and methods of the present invention relate to optical devices such as an active reflective polarizer or an optical shutter and a liquid crystal display (LCD) employing the active reflective polarizer, and more particularly, to a large size active reflective polarizer, which can be easily manufactured, and an LCD employing the large active reflective polarizer.
2. Description of the Related Art
FIG. 1 is a perspective view of the wire-grid polarizer 16. Referring to FIG. 1, the wire-grid polarizer 16 includes a transparent substrate 16a and conductive metal wires 16b arranged at regular intervals in parallel to one another on the transparent substrate 16a. The wire-grid polarizer 16 acts as a diffraction grating when the pitch P of the metal wires 16b is greater than the wavelength of light, and acts as a polarizer when the pitch P of the metal wires 16b is less than the wavelength of the light. In the latter case, the wire-grid polarizer 16 reflects light having a polarization component parallel to the metal wires 16b and transmits light having a polarization component perpendicular to the metal wires 16b. 
In order for the wire-grid polarizer 16 to act as a polarizer in a visible light range, the pitch P of the metal wires 16b should be less than about 100 nm. The electron beam lithography (E-beam litho), a widely used lithographic technique in semiconductor industry, has been used to arrange the metal wires 16b at such a narrow pitch P at the laboratory levels. This technique, however, is a very costly and slow process that may not be much of an issue in semiconductor industry which deals with devices at the scale of typical microns, but becomes a serious issue when producing wire-grid polarizer to be used in displays, which surface area typically scales from a few to hundreds of squared centimeters (cm2). Although small wire-grid polarizers usable in a visible light range have been manufactured in laboratories (with application of E-beam litho), manufacturing technology for mass production of large sized wire-grid polarizers suitable for display devices is yet to be developed.